1. Field of the Invention
The present invention relates to an earmuff and a headphone having a structure of the earmuff, and more particularly, the present invention relates to an earmuff and a headphone in which a large volume of a front air chamber can be secured by providing an air-permeable member between a baffle board and an ear pad.
2. Description of the Related Art
A longitudinal cross-sectional view of a conventional earmuff is exemplary illustrated in FIG. 5. As illustrated in FIG. 5, in an earmuff 60, an ear pad 63 is fixed to a baffle board 62 that covers an opening of an ear cup 61. A front air chamber 64 is a space surrounded by the baffle board 62 and the ear pad 63 and is in communication with an external auditory meatus of a wearer.
The baffle board 62 has a shape in which two torus-shaped members having an outer diameter different from each other are separated in an axial direction. The front torus-shaped member has a flange 621 formed on an outer periphery. A flap 631 that is a part of a skin member of the ear pad 63 covers the flange 621. The flap 631 is made of a flexible material. With the flexibility, the flap 631 is attached and engaged to the flange 621. The flap 631 may incorporate rubber material and may cover the flange 621 with expansion and contraction of the rubber material to be engaged thereto.
The ear pad 63 is fixed to the baffle board 62 with the flap 631 covering the flange 621. The baffle board 62 has a groove 622 formed on the entire periphery thereof at a portion between the flange 621 and the outer edge of the baffle board 62 body.
A headband, not illustrated in the figure, is attached to the earmuff 60 at the outer side of the ear cup 61. The headband is made of an elastic material and applies pressing force in the direction towards the ear pad 63. On the other end of the headband, another earmuff 60 is attached in an opposing manner, thereby forming a pair.
In a conventional earmuff having the above described structure, the ear pad is pressed to an auricle or a skin therearound of a wearer to be in close contact thereto, with pressing force applied by a headband. Thus, the earmuff has external noise insulation property. A headphone in which a speaker unit is provided to an earmuff having the above described structure can prevent output sound from leaking outside. Sound insulation property of such an earmuff can be effectively improved by providing a large ear pad.
However, a large ear pad increases the size of an earmuff as a whole, thereby making it less comfortable for the user. Moreover, the size of an ear pad cannot be increased over a certain level.
A headphone is known having an improved sound insulation property without increasing the size of an ear pad (see, for example, Japanese Patent Application Publication 2009-17176). In the headphone, a front air chamber not in communication with a rear air chamber is secured so that attenuation of transmission of received external noise can be improved.
A front air chamber plays a significant roll in improving sound insulation property of an earmuff. A larger volume of a front air chamber provides higher sound insulation property. In the conventional earmuff 60 as shown in FIG. 5, the volume of the front air chamber 64 is compromised as much as the depth of the groove 622, i.e., the distance from the periphery of the baffle board 62 to the bottom of the groove 622. Thus, the volume of the front air chamber 64 and the sound insulation is limited.
In the headphone disclosed in Japanese Patent Application Publication No. 2009-17176, the volume of the front air chamber is secured with the thickness of the ear pad. Still, with the ear pad being compressed by pressing force applied by the headband while the headphone is worn, the volume of the front air chamber becomes small.
The volume of a front air chamber can be made large by providing a hole that communicates the internal space of an ear pad with the front air chamber at a portion of the ear pad on the front air chamber side. Unfortunately, a hole on an ear pad transmits received external noise and insulation against noises in certain frequencies dramatically changes. Further, in a headphone with the internal space of an ear pad communicated with a front air chamber communicating with an outer auditory meatus, reproduced sound is more likely to be leaked outside, and thus sound insulation towards the outside is low.